<button class="btn">
  <span class="left-span"></span>
  <p class="text-btn">Hover me</p>
  <p class="hidden-text-btn">Thank you!</p>
  <span class="right-span"></span>
</button>

<style>
/* From Uiverse.io by sashadubovyi  - Tags: simple, animation, success, button */
.btn {
  cursor: pointer;
  position: relative;
  padding-left: 30px;
  padding-right: 30px;
  padding-top: 10px;
  padding-bottom: 10px;
  font-size: 20px;
  font-weight: 400;
  border: none;
  display: flex;
  align-items: center;
  background: transparent;
  color: #f93d21;
  transition: all 100ms;
  overflow: hidden;
  height: 50px;
  width: 170px;
}

.left-span {
  position: absolute;
  left: 0;
  height: 50px;
  width: 15px;
  border-top: 1px solid #f93d21;
  border-bottom: 1px solid #f93d21;
  border-left: 1px solid #f93d21;
  transition: all 500ms;
}

.right-span {
  position: absolute;
  right: 0;
  height: 50px;
  width: 15px;
  border-top: 1px solid #f93d21;
  border-bottom: 1px solid #f93d21;
  border-right: 1px solid #f93d21;
  transition: all 500ms;
}

.text-btn {
  position: absolute;
  transform: translateX(0px);
  width: 110px;
  transition: all 200ms;
}

.hidden-text-btn {
  position: absolute;
  transform: translateX(150px);
  opacity: 0;
  transition: all 200ms;
}

.btn:hover .text-btn {
  transform: translateX(-150px);
  opacity: 0;
}

.btn:hover .hidden-text-btn {
  transform: translateX(0px);
  opacity: 1;
}

.btn:hover .right-span,
.btn:hover .left-span {
  width: 100%;
}

</style>
    